Thread delivery mechanism



Jan.27,1970' M. SCHLUMPF 3,491,963

THREAD DELIVERY MECHANISM Filed May 7, 1968 2 Sheets-Sheet 1 Fig.1 3 Fig.2 i 3 INVENTOR.

MM. SCHLUMPF MW! M W hrroeueis Jan. 27, 1970 M. SCHLUMPF 3,491,963

THREAD DELIVERY MECHANISM Filed May 7, 1968 I I 2 sheets-Sheet z INVENTOR.

MW M W United States Patent 3,491,963 THREAD DELIVERY MECHANISM Max Schlumpf, Uetikon am See, Zurich, Switzerland, assignor to Maschinenfabrik Scharer, Zurich, Switzerland Filed May 7, 1968, Ser. No. 727,261 Claims priority, application Switzerland, Sept. 26, 1967, 13,411/ 67 Int. Cl. B65h 51/30 US. Cl. 242--47.01 6 Claims ABSTRACT OF THE DISCLOSURE A rotating roll or drum has its cylindrical surface looped by the thread to be delivered, the circumferential speed of the roll or drum being greater than the travelling speed of the thread, and the cylindrical surface of the roll or drum is provided with surface portions of different surface finish to provide a relatively greater surface roughness at one axial end of the roll or drum and a relatively smaller surface roughness at the opposite axial end of the roll or drum, a thread guide being provided which is adapted to move towards and away from said roll or drum surface in response to the tension of the thread, in order to cause axial displacement of the thread loops on said roll or drum surface to vary the frictional resistance acting on the thread loops.

This invention relates to thread delivery mechanism for the automatic regulation of the thread tension, having a rotating drum with the thread to be delivered looping around the surface of the drum, the circumferential speed of the drum being greater than the travelling speed of the thread.

Delivery mechanisms of this type are used for example with winding machines in order to compensate the winding-off tension of the thread and to deliver the thread with a rather low and uniform tension towards the bobbin or package to be formed.

The Swiss patent specification No. 411,656 discloses a thread delivery mechanism of the above mentioned type, in which two thread guides are provided at the ends of pivoting arms. The two arms, and accordingly the two thread guides are urged away from each other by the action of a spring. The position of the two thread guides determines the angle of winding of the thread about a drum. When the thread tension increases, the two thread guides approach each other, whereby the angle of winding of the thread about the drum, and accordingly the driving force acting on the unwinding thread is increased, causing a decrease of the tension of the thread delivered by the mechanism.

Though an automatic compensation of the thread tension is obtained with this known type of delivery mechanism, the possibilities of regulation are limited, because the angle of winding of the thread on the drum can be varied in a limited amount only, and for example can never be doubled.

It is an object of the present invention to provide a thread delivery mechanism in which the driving force acting on the thread can be automatically regulated within an extended range.

According to the invention, the surface of the drum about which the thread to be delivered is looped is provided with a surface finish of varying frictional properties, the surface roughness being the greatest adjacent one axial end of the drum surface and the smallest adjacent the other axial end of the drum, a thread guide being arranged to be movable relative to said drum in response to the tension of said thread to cause a displacement of the thread loops on the drum surface in a direction axially of the drum.

While the thread which may form several loops around the drum, is passed over regions of the cylindrical drum surface with a greater or smaller surface roughness, the coefficient of friction ,u appearing in the exponent of power in the equation of rope friction changes. The surface finish of the drum can be such that the friction coefiicient and accordingly the exponent of power can increase to a multiple of its smallest value.

The invention will now be more fully described with reference to the accompanying drawings, in which:

FIGURE 1 shows an embodiment of a thread delivery mechanism in plan view and in a first position of operation;

FIGURE 2 is a plan view of the thread delivery mechanism in a second position of operation;

FIGURE 3A and 3B are views in front and side elevation of the mechanism;

FIGURE 4 represents the development of the outer cylindrical surface of the delivery roller of the mechanism;

FIGURES 5 and 6 represent developments of modified delivery roller surfaces.

Referring to FIGS. 1 to 4 of the drawings, the represented thread delivery mechanism comprises a cylindrical casing 2 in which a driving shaft 3 is rotatably mounted in a roller bearing, not shown. The driving shaft 3 projects with both ends from the casing 2. A roller or drum 1 is detachably mounted on the front end of the shaft 3 in driving connection with the shaft. A plate-shaped bracket 4 is secured to the end portion of the casing 2 facing the roller 1. This bracket 4 serves for mounting the delivery mechanism for example on the frame of a winding machine in such manner that the shaft 3 extends in horizontal direction. On the lower side of the bracket 4 and at the left side of the roller or drum 1 as seen in FIGS. 1, 2 and 3A, a wire thread or pig tail guide 16 forming a loop is fixed to the bracket. A rod-shaped cylindrical thread guide or rod 5 is secured to the bracket 4 at the right side of the roller 1. In its normal operating position (FIG. 1), the thread guide 5 extends parallel to the roller 1. The thread guide 5 is carried by a collar 20 pivotally mounted on a pin 6 extending at right angles to the axis of the roller 1. The pin 6 is carried by a supporting lug 12 on the bracket 4. A disc 8 having a knurled or toothed edge and provided with a cylindrical extension 19 is rotatably mounted on the pin 6. The cylindrical extension 19 bears against the rear face of the collar 20 of the thread guide 5. Two screw nuts 9 serve to hold the disc 8 and extension 19 on the threaded end of the pin 6. A spring 7 is wound about the cylindrical extension 19. One spring end is fixed to the knurled disc 8 and the other spring end to the rear face of the collar 20, A stationary holding member 10 of wire is provided to coact with the knurled or toothed edge of the disc 8 and is clamped between the two nuts 9, in order to hold the disc 8 in its angular position. The rear face of the collar 20 is provided with a projecting pin 11 cooperating with two angularly spaced fixed abutments 21 on the supporting lug 12. The spring 7 has the tendency to urge the collar 20 carrying the thread guide 5 against one of the two angularly spaced abutments 21. By turning the disc 8, the tension of the spring 7 can be varied.

It has been represented in FIGS. 1, 2 and 4 that the metal roller 1 is divided in a plurality of zones 13, 14 having a different surface finish. The lower end portion of the roller is provided with a plurality of zones 14 of triangular or inverted V-shape which, at the free end of the roller, join each other 'by their base edge. These zones 14 extend into zones 13 of V-shape with the summit of the V situated at the lower edge of the roller. The surface of the zones 13 and 14'are' of different roughness, the zone 13 being of a rougher finish and having a dull appearance, while the zones 14 are smoother and have a glossy appearance. In other words, the surface portions 14 are polished, and the surface portions 13 have a mat finish. The thread guide preferably is coated with plastic.

The operation of the described thread delivery mechanism is as follows: The synthetic thread 15 arriving from a bobbin to be unwound runs through the loops of the wire thread guide 16 and is wound twice about the delivery roller 1 and the thread guide 5 and then it abandons the roller in upward direction (FIG, 3A).

The delivery roller 1 is rotated by the shaft 3 at a circumferential speed which is greater than the travelling speed of the moving thread 15.

Upon an increase of tension in the thread strand running-up on the roller 1 and thread guide 5, the thread guide is tilted by the thread tension out of its normal position shown in FIG. 1 towards the drum 1 into the position shown in FIG. 2, whereby the loops of the thread will slide along the thread guide and the drum towards the free end thereof into a zone of improved driving action of the drum on the thread until the desired thread tension readjusts again. When the thread tension decreases, the spring 7 will cause the thread guide to return into its original position according to FIG. 1.

It is well known that the coeflicient of friction of synthetic threads is small with dull surfaces and greater with glossy surfaces, i.e. the coeflicient of friction decreases when the surface roughness increases.

FIG. 5 show the development of the drum surface with a modified surface finish. The drum surface is provided with two strip-shaped zones 17 and 18 of different surface finish, the zone 17 being rough and the zone 18 smooth. According to FIG. 6, the degree in smoothness or roughness of the drum surface 22 changes gradually from one end of the drum towards the other end.

I claim:

1. A thread delivery mechanism for automatic regu lation of the thread tension, having a rotating drum with said-drum, the circumferential speed of the" drum being greater than the travelling speed of the thread, wherein the improvement consists in said drum surface looped by the thread being provided with a surface finish of varying frictional properties, the surface roughness being the greatest adjacent one axial end of the operating range of the drum surface and the smallest adjacent the other axial end of the drum, a thread guide being arranged to be movable relative to said drum in response to the tension of said thread to cause a displacement of the thread loops on the drum in a direction axially of the drum.

2. A thread delivery mechanism according to claim 1, in which said thread guide is formed by a rod extending parallel with the axis of said drum, said thread guide being pivotally mounted with one of its ends to be tiltable against spring action towards the drum about an axis extending at right angles to the drum axis.

3. A thread delivery mechanism according to claim 1, in which the cylindrical surface of said drum is divided into circumferentially extending, strip-shaped zones of different surface roughness.

4. A thread delivery mechanism according to claim 1, in which the cylindrical surface of the drum is provided with circumferentially adjacent zones of different surface roughness arranged in axially intermeshing relation.

5. A thread delivery mechanism according to claim 1, in which the surface roughness of the drum is substantially constant in circumferential direction of the drum and continuously decreases in axial direction towards one end of the axial operating range of the drum.

6. A thread delivery mechanism according to claim 2, in which said thread guide is angularly movable between two fixed abutments.

References Cited UNITED STATES PATENTS 2,798,593 7/1957 Lowe et al. 24247.03 3,020,621 2/1962 Sacks. 3,390,840 7/1968 Barnett 24247.01

NATHAN L. MINTZ, Primary Examiner 

